📖 Book
✓ Link checked
Paid
Beginner
Why we picked it
The single best thing ever written on customer conversations. It teaches you to ask about the customer's life and past behaviour, not your idea, so you can't be lied to. If a founder reads one thing before talking to a single customer, it's this.
From
momtestbook.com
by Rob Fitzpatrick
~130 pages
- Talk about their life, not your idea.
- Ask about specifics in the past, not opinions about the future.
- 'That's so cool, I'd totally buy it' is a compliment, not data, dig for commitment and evidence.
Open
momtestbook.com →
✍️ Essay
✓ Link checked
Free
Beginner
Why we picked it
The definitive essay on where good ideas come from: notice problems you personally have, don't force it. Use it as the lens for judging whether your idea is a real problem or a solution in search of one.
From
paulgraham.com
by Paul Graham
~20 min read
- Live in the future and build what's missing.
- The best ideas look like bad ideas at first (schleps and hard-to-explain).
- Start with problems you have, in a domain you actually know.
Open
paulgraham.com →
📄 Article
✓ Link checked
Free
Intermediate
Why we picked it
Turns the vague feeling of product-market fit into a number you can move. Ask users how they would feel if they could no longer use the product, then track the share who say 'very disappointed'. Under 40 percent means keep working. A test you can run on an idea long before you scale it.
From
First Round Review
by Rahul Vohra
~20 min read
- The 40 percent 'very disappointed' benchmark for product-market fit.
- Segment to your high-expectation customers and build for them.
- Make the fit score a metric you improve quarter by quarter.
Open
review.firstround.com →
✍️ Essay
✓ Link checked
Free
Intermediate
Why we picked it
The essay that put 'product-market fit' into the startup vocabulary. Read it for the gut-level description of what PMF feels like when it's happening vs when it isn't, the intuition behind the metrics.
From
pmarchive.com
by Marc Andreessen
~15 min read
- Market matters most; a great market pulls product out of a startup.
- You can feel PMF, customers buy as fast as you can ship.
- Before PMF, do whatever it takes to get there; nothing else counts.
Open
pmarchive.com →
✍️ Essay
✓ Link checked
Free
Beginner
Why we picked it
Seibel's whole point is that a market only counts once real customers are grabbing the product as fast as you can make it and paying for it, not because a report says the category is big. That is the exact test for your situation: a huge paper market with almost nobody paying is the opposite of the hair-on-fire demand he describes. Read it as a gut-check on whether you have found a real problem or just a large-sounding one.
From
Michael Seibel (Y Combinator)
by Michael Seibel
~4 min read
- Real product market fit shows up as customers desperate to use and pay for the product, not as a big total-addressable-market slide.
- If usage is calm and nobody is paying, you almost certainly have not found the burning problem yet, however large the market looks.
- A small group of customers who love you beats a large group who kind of like you.
Open
michaelseibel.com →
📄 Article
✓ Link checked
Freemium
Intermediate
Why we picked it
Once you are testing an idea, this piece gives you concrete signals that tell you whether it is actually working, from retention curves to organic word of mouth. It collects how experienced founders and investors describe the moment an idea starts to land. Read it so you know what evidence to look for instead of guessing whether the idea is good.
From
Lenny's Newsletter
by Lenny Rachitsky
about 15 min read
- Retention that flattens rather than falling to zero is the clearest signal
- Organic growth and referrals show the problem was real
- If people would be very disappointed to lose it, you are onto something
Open
lennysnewsletter.com →
📄 Article
✓ Link checked
Freemium
Beginner
Why we picked it
The qualitative half of the answer, told through founders describing the moment things flipped: inbound you cannot keep up with, servers falling over, customers telling their friends without being asked. It is useful precisely because the feeling arrives before the metrics confirm it. Read it to recognize the pull when it starts.
From
Lenny's Newsletter
by Lenny Rachitsky
~2,000 words
- PMF often feels like demand you struggle to keep up with
- Word of mouth spreading on its own is a core tell
- The feeling usually precedes the metrics catching up
Open
lennysnewsletter.com →
✍️ Essay
✓ Link checked
Free
Beginner
Why we picked it
Steve Blank is the person who most clearly made the case against planning everything and then unveiling it in one big moment. His argument is that the plan you build before you talk to real customers is mostly untested assumptions, so a loud coordinated launch bets the company on guesses. If your co-founder wants the big reveal, this is the sharpest starting point for why shipping quietly and learning first is usually the safer bet.
From
steveblank.com
by Steve Blank
5 min read
- A launch plan built before real customer contact is a list of assumptions, not facts, so treat it as something to test rather than execute.
- Iterative, cohort-by-cohort rollout lets you fix the product and the messaging before you spend on reach.
- The big-bang launch magnifies whatever you got wrong, because you find out at scale instead of quietly.
Open
steveblank.com →
📖 Book
✓ Link checked
Paid
Beginner
Why we picked it
Savoia, who led early Google AdWords, argues most ideas fail because nobody wanted them, and teaches pretotyping: cheap experiments that generate your own data on real demand before you build. You get concrete tactics like the fake-door and the mechanical-turk test, plus a way to demand skin-in-the-game commitment rather than opinions. Practical for anyone who wants a test that can prove them wrong.
From
Alberto Savoia
by Alberto Savoia
~250 pages
- Collect your own data on real behaviour instead of trusting opinions
- Pretotype the idea to test demand before you build a prototype
- Measure commitments like a signup or a payment, not verbal enthusiasm
Open
albertosavoia.com →
📄 Article
✓ Link checked
Free
Intermediate
Why we picked it
A first-hand account of how a founder recruited a small group of likely buyers, shipped the most basic thing, and iterated on weekly feedback. It shows the exact move our answer recommends: stop interviewing, put a working thing in a few real hands. Concrete and repeatable rather than theoretical.
From
Intercom Blog
by Garrett Moon
- Recruit a small group of highly likely buyers early
- Ship the most basic working version, then iterate on feedback
- Keep a continuous feedback loop while you build the real thing
Open
intercom.com →
✍️ Essay
✓ Link checked
Free
Beginner
Why we picked it
Jackson's test is blunt and useful: can you name five specific real people who need this and would buy it. If you cannot, you have not validated, you have guessed. It is a five minute reality check that matches our short answer almost word for word.
From
justinjackson.ca
by Justin Jackson
- Write down five real people by name who need it
- If you cannot name them, you are still guessing
- Being connected to the customer's community is the real signal
Open
justinjackson.ca →
📖 Book
✓ Link checked
Paid
Beginner
Why we picked it
The origin text for the modern MVP and validated-learning vocabulary every founder now uses. Read it for the mental model that a startup is a series of experiments, not a single bet.
From
theleanstartup.com
by Eric Ries
~330 pages
- Progress = validated learning, not features shipped.
- Run the Build-Measure-Learn loop as fast as you can.
- An MVP is a learning tool, not a cheap product.
Open
theleanstartup.com →
Why we picked it
The permission slip to recruit users by hand, do things manually, and deliver 'insanely great' experiences to your first few customers. The cheapest, most honest way to validate demand is to go get it one person at a time.
From
paulgraham.com
by Paul Graham
~15 min read
- Recruit your first users manually, don't wait for them to come.
- A tiny group of users who love you beats a big group who like you.
- Manual, unscalable effort early is a feature, not a failure.
Open
paulgraham.com →
